> Twist do you think happens to every city that has reached 16 million people?

It's not about the exact number, it's that one city is not going to 10x in population from getting the price of housing down to "still a city but not skyrocketing".

> I’m confused on why you think paris is affordable

Compared to San Diego, it does seem to be significantly more affordable, and mainly because of rent.

> and San Diego metro could somehow have enough water

The most expensive source of water, desalination, should be under $1 per day per person. And there's probably better options.

> to grow to 220 million.

That number is a silly number to explain density, not a proposal.

> and if you think that those cities are affordable…

No, the only comparison point was Paris, and the density of Paris.

There is no way for San Diego to grow that fast overnight anyways. If it grows gradually, and it’s still desirable, that will attract more jobs and more people eventually, the city won’t become more affordable (long term) until it stops attracting new residents. Otherwise, new housing simply provides temporary relief while the city grows.

Paris is a good example, I think, of a city expensive by French standards. My point was that if your theory is you can build to affordable, there should be at least one example on the planet where that actually worked (even Tokyo is considered expensive by Japanese standards).

> the city won’t become more affordable (long term) until it stops attracting new residents

I really hope we don't have indefinite large amounts of US population growth. And if we mostly stabilize the population, then it only takes a few 16M cities to absorb all the demand and make the relief permanent.

> Paris is a good example, I think, of a city expensive by French standards. My point was that if your theory is you can build to affordable, there should be at least one example on the planet where that actually worked (even Tokyo is considered expensive by Japanese standards).

Then consider this particular argument not that you can build to a nebulously defined "affordable", but that you can build to "San Diego has between 100% and 1000% of its current population with rent 40% lower than it is right now".

> I really hope we don't have indefinite large amounts of US population growth.

You don't need indefinite growth. People generally want to live in a few cities; e.g. they don't really want to live in Toledo, they want to live in San Deigo. So you just have to let people live where they want to live, not where they have to lvie.

> Then consider this particular argument not that you can build to a nebulously defined "affordable", but that you can build to "San Diego has between 100% and 1000% of its current population with rent 40% lower than it is right now".

That has literally never happened before and I don't see how it will happen first in San Diego. Mega cities get more expensive, not cheaper, as they grow, since the concentration of human capital and jobs make it even more valuable to live there.

I'll put it this way. If 10-20 popular cities try to outbuild their population growth with a cap of 16 million people each, at least some of them will succeed. Three quarters of the US population isn't going to move into 10-20 cities.

The only way that general idea fails is if the demand concentrates so strongly into a couple megacities that we don't even have 10-20 non-obsolete cities left. That seems unlikely to me.

San Diego would be a very popular city at lower prices, but simply put there isn't enough population in the US to even think that demand could grow anywhere close to those levels. It would take a 50 year long gold rush, draining of other American cities, etc. The fastest growing city in modern history, Shenzen, grew 6000% in 30 years, and it could only do so because China simultaneously had the highest population growth in the world and the highest urbanization rate in the world.

At some point, demand is saturated, and it takes an extremely delusional belief that demand can perpetually grow so that prices never drop. We have proof in the article that prices can drop with even moderately fast construction rates. Keep going.